An exostosis, also known as bone spur, is the formation of new
bone
A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...
on the surface of a bone. Exostoses can cause chronic pain ranging from mild to debilitatingly severe, depending on the shape, size, and location of the lesion. It is most commonly found in places like the ribs, where small bone growths form, but sometimes larger growths can grow on places like the ankles, knees, shoulders, elbows and hips. Very rarely are they on the skull.
Exostoses are sometimes shaped like
spur
A spur is a metal tool designed to be worn in pairs on the heels of riding boots for the purpose of directing a horse or other animal to move forward or laterally while riding. It is usually used to refine the riding aids (commands) and to back ...
s, such as
calcaneal spur
A calcaneal spur (also known as a heel spur) is a bony outgrowth from the calcaneal tuberosity (heel bone). Calcaneal spurs are typically detected by x-ray examination. It is a form of exostosis.
When a foot is exposed to constant stress, calci ...
s.
Osteomyelitis
Osteomyelitis (OM) is an infection of bone. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The long bones of the arms and legs are most commonly involved in children e.g. the femur and humerus, while the ...
, a bone infection, may leave the adjacent bone with exostosis formation.
Charcot foot, the neuropathic breakdown of the feet seen primarily in
diabetics
Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level (hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased a ...
, can also leave bone spurs that may then become symptomatic.
They normally form on the bones of joints, and can grow upwards. For example, if an extra bone formed on the ankle, it might grow up to the shin.
When used in the phrases "cartilaginous exostosis" or "osteocartilaginous exostosis", the term is considered synonymous with
osteochondroma
Osteochondromas are the most common benign tumors of the bones.
The tumors take the form of cartilage-capped bony projections or outgrowth on the surface of bones exostoses. It is characterized as a type of overgrowth that can occur in any bone w ...
. Some sources consider the two terms to mean the same thing even without qualifiers, but this interpretation is not universal.
Osteophytes
Osteophyte
Osteophytes are exostoses (bony projections) that form along joint margins. They should not be confused with enthesophytes, which are bony projections that form at the attachment of a tendon or ligament. Osteophytes are not always distinguished ...
s are bone spurs that develop on the margins of joints secondary to external stimuli such as
osteoarthritis
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the w ...
.
However, these are not always distinguished from exostoses in any definite way.
Fossil record
Evidence for exostosis found in the fossil record is studied by
paleopathologists
Paleopathology, also spelled palaeopathology, is the study of ancient diseases and injuries in organisms through the examination of fossils, mummified tissue, skeletal remains, and analysis of coprolites. Specific sources in the study of ancient ...
, specialists in ancient disease and injury. Exostosis has been reported in dinosaur fossils from several species, including ''
Acrocanthosaurus atokensis
''Acrocanthosaurus'' ( ; ) is a genus of carcharodontosaurid dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous, from 113 to 110 million years ago. Like most dinosaur genera, ...
'', ''
Albertosaurus sarcophagus
''Albertosaurus'' (; meaning "Alberta lizard") is a genus of tyrannosaurid theropod dinosaurs that lived in western North America during the Late Cretaceous Period, about 71 million years ago. The type species, ''A. sarcophagus'', was app ...
'', ''
Allosaurus fragilis
''Allosaurus'' () is a genus of large carnosaurian theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic epoch ( Kimmeridgian to late Tithonian). The name "''Allosaurus''" means "different lizard" alludi ...
'', ''
Gorgosaurus libratus
''Gorgosaurus'' ( ; ) is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period (Campanian), between about 76.6 and 75.1 million years ago. Fossil remains have been found in the Ca ...
'', and ''
Poekilopleuron bucklandii
''Poekilopleuron'' (meaning "varied ribs") is a genus of tetanuran dinosaur, which lived during the middle Bathonian of the Jurassic, about 168 to 166 million years ago. The genus has been used under many different spelling variants, although on ...
''.
Hereditary multiple exostoses
Hereditary multiple exostoses
Hereditary multiple osteochondromas (HMO), also known as hereditary multiple exostoses, is a disorder characterized by the development of multiple benign osteocartilaginous masses ( exostoses) in relation to the ends of long bones of the lower li ...
(HME), also called hereditary multiple osteochondromas (HMO), is a condition that is estimated to affect 1 in 50,000 individuals. Multiple benign or noncancerous bone tumors develop in the affected individuals. The number and location vary among affected patients. Most people seem unaffected at birth; however, by the age of 12 years, they develop multiple exostoses. Affected individuals commonly complain of palpable and recognizable lumps (exostoses) at about the knees and in the forearms. The condition characteristically occurs bilaterally. It may lead to mild degrees of growth retardation and limb asymmetry.
Genu valgum Genu, a Latin word for "knee," may refer to:
* Genu of internal capsule
* Genu of the corpus callosum
* Genu recurvatum
* Genu valgum
* Genu varum
Genu varum (also called bow-leggedness, bandiness, bandy-leg, and tibia vara) is a varus def ...
(commonly known as "knock-knees"), ankle valgus, and bowing and shortening of one or both of the forearm bones are common manifestations.
Types
*
Buccal exostosis
A buccal exostosis is an exostosis (bone prominence) on the buccal surface (cheek side) of the alveolar ridge of the maxilla or mandible. More commonly seen in the maxilla than the mandible, buccal exostoses are considered to be site specific. Exi ...
*
Footballer's ankle (exotosis of the ankle bone)
*
Hereditary multiple exostoses
Hereditary multiple osteochondromas (HMO), also known as hereditary multiple exostoses, is a disorder characterized by the development of multiple benign osteocartilaginous masses ( exostoses) in relation to the ends of long bones of the lower li ...
(HME)
*
Subungual exostosis
*
Surfer's ear
Surfer's ear is the common name for an exostosis or abnormal bone growth within the ear canal. Surfer's ear is not the same as swimmer's ear, although infection can result as a side effect.
Irritation from cold wind and water exposure causes th ...
(exostosis of the ear canal)
*
Torus mandibularis
Torus mandibularis is a bony growth in the mandible along the surface nearest to the tongue. Mandibular tori are usually present near the premolars and above the location of the mylohyoid muscle's attachment to the mandible. In 90% of cases, ther ...
*
Torus palatinus
A torus palatinus (pl. tori palatini), or palatal torus (pl. palatal tori), is a bony protrusion on the palate. Palatal tori are usually present on the midline of the hard palate.Neville, B.W., D. Damm, C. Allen, J. Bouquot. ''Oral & Maxillofaci ...
*
Calcaneal spur
A calcaneal spur (also known as a heel spur) is a bony outgrowth from the calcaneal tuberosity (heel bone). Calcaneal spurs are typically detected by x-ray examination. It is a form of exostosis.
When a foot is exposed to constant stress, calci ...
(heel spur)
See also
*
Ganglion cyst
A ganglion cyst is a fluid-filled bump associated with a joint or tendon sheath. It most often occurs at the back of the wrist, followed by the front of the wrist. Onset is often over several months, typically with no further symptoms. Occasional ...
*
*
Osteoma
An osteoma (plural: "osteomata") is a new piece of bone usually growing on another piece of bone, typically the skull. It is a benign tumor.
When the bone tumor grows on other bone it is known as "homoplastic osteoma"; when it grows on other tissu ...
*
Osteosclerosis
Osteosclerosis is a disorder that is characterized by abnormal hardening of bone and an elevation in bone density. It may predominantly affect the medullary portion and/or cortex of bone. Plain radiographs are a valuable tool for detecting and ...
*
Pachyosteosclerosis
Pachyosteosclerosis is a combination of thickening (pachyostosis) and densification (osteosclerosis) of bones. It makes bones more heavy, but also more fragile. The condition often occurs in aquatic vertebrates, especially those living in shallow w ...
*
Pachyostosis
Pachyostosis is a non-pathological condition in vertebrate animals in which the bones experience a thickening, generally caused by extra layers of lamellar bone. It often occurs together with bone densification (osteosclerosis), reducing inner ca ...
References
External links
The Ear and Balance Center The Sonos Group
MHE Research Foundation(Multiple Hereditary Exostoses)
{{Osteochondropathy
Skeletal system
et:Kooljaluu
pt:Exostose